GLUCOSE AND OXYGEN UTILIZATION IN SYMPATHETIC GANGLIA 



103 



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Fig. 12. Survival of postganglionic response in superior cervical ganglia excised 

 from rats. Ganglia were placed in stirred solutions containing various substrates. The 

 preganglionic nerve was stimulated supramaximally once every few minutes to test 

 the capacity to respond. Time in hours after withdrawing glucose (upper graphs) or 

 hours after excision (middle and lower graphs). Concentration of lactate, approxi- 

 mately 5.6 mM; of glucose, 5.5 mM. 



Maintenance of oxygen consumption. Considering the evidence that glucose 

 is the main substrate for resting metabolism, and the fact that capacity for 

 function is lost when glucose is absent, it would be reasonable to expect that 

 the rate of oxygen consumption should decline considerably following with- 

 drawal of glucose. This is not at all what happens, at least for the first two 

 hours after removal of glucose. During this period, in which the functional 

 abilities of the neurons are drastically and largely irreversibly reduced or abol- 

 ished, oxygen utilization is relatively unaltered. This observation, previously 

 reported (Larrabee and Bronk, 1952), has recently been confirmed with 

 improved techniques, including sterile conditions. Never did the rate of oxygen 

 consumption fall more than 20% during the first two hours after withdrawal 

 of glucose, and the change was usually much less than this. On the average 

 oxygen uptake dropped only about 10 % 2 . Oxygen consumption at a rate inde- 

 pendent of glucose supply has been observed in the cerebral cortex of cats 

 under conditions of perfusion by Grenell and Davies (1950). 



2 For additional details from more recent experiments concerning oxygen consump- 

 tion, see Larrabee, Horowicz, Stekiel, and Dolivo, 1956. 



